Atmospheric Nuclear Weapons Testing

Transcription

1 Battlefield of the Cold War The Nevada Test Site Volume I Atmospheric Nuclear Weapons Testing United States Department of Energy

2 Of related interest: Origins of the Nevada Test Site by Terrence R. Fehner and F. G. Gosling The Manhattan Project: Making the Atomic Bomb * by F. G. Gosling The United States Department of Energy: A Summary History, * by Terrence R. Fehner and Jack M. Holl * Copies available from the U.S. Department of Energy 1000 Independence Ave. S.W., Washington, DC Attention: Office of History and Heritage Resources Telephone:

3 DOE/MA-0003 Terrence R. Fehner & F. G. Gosling Office of History and Heritage Resources Executive Secretariat Office of Management Department of Energy September 2006

4 Battlefield of the Cold War The Nevada Test Site Volume I Atmospheric Nuclear Weapons Testing Volume II Underground Nuclear Weapons Testing (projected) These volumes are a joint project of the Office of History and Heritage Resources and the National Nuclear Security Administration.

5 Acknowledgements Atmospheric Nuclear Weapons Testing, Volume I of Battlefi eld of the Cold War: The Nevada Test Site, was written in conjunction with the opening of the Atomic Testing Museum in Las Vegas, Nevada. The museum with its state-of-the-art facility is the culmination of a unique cooperative effort among cross-governmental, community, and private sector partners. The initial impetus was provided by the Nevada Test Site Historical Foundation, a group primarily consisting of former U.S. Department of Energy and Nevada Test Site federal and contractor employees. The foundation worked with the Department s National Nuclear Security Administration, the State of Nevada, and a local non-profit, the Desert Research Institute, to bring to fruition a mixed-use, public outreach facility that benefits all concerned parties. The facility houses the museum, the Department s public reading room and Nuclear Testing Archive, and office space utilized partially for cultural resources/historic preservation activities at the Nevada Test Site. Similarly, Atmospheric Nuclear Weapons Testing represents a unique collaboration between the Atomic Testing Museum and two headquarters offices and a field office of the Department of Energy. The Atomic Testing Museum provided the original inspiration for the project and access to museum artifacts and photographs. The Department s National Nuclear Security Administration provided funding for researching and printing the history. The Nevada Site Office offered support and resources throughout the researching and writing of the history. The Office of History and Heritage Resources of the Department s Executive Secretariat researched and wrote the history. Terrence R. Fehner is a senior historian and the Department s Deputy Federal Preservation Officer working in the Office of History and Heritage Resources. F.G. Gosling is the Department s Chief Historian and Federal Preservation Officer. The authors wish to thank the many individuals who offered comments, support, and assistance. They made this work possible and helped make it a better and more complete history. Darwin Morgan served as the primary point of contact for the Nevada Site Office and the National Nuclear Security Administration. Michael W. Brown of the Nevada Site Office also provided assistance. At the Atomic Testing Museum, Director William G. Johnson provided full access to the museum resources and responded promptly and completely to all requests by the authors. Vanya Scott and Maggie Smith of the museum were unstinting in offering their time and effort. Without the constant support of Troy Wade, former assistant secretary for defense programs at the Department and president/chairman of the Nevada Test Site Historical Foundation, this history would not have been written. iii

6 Martha DeMarre at the Department s Nuclear Testing Archive in Las Vegas and her staff, especially Jeff Gordon, Bob Furlow, and Terry Wade, provided the authors with hundreds of unpublished documents, newspaper articles, and reports. They were the primary source for the photographs used in this history. They also offered sound advice on further avenues of research. Janice Langley and Richard Reed at the Remote Sensing Laboratory helped locate photographs and processed our requests for high resolution copies. The Department s Office of Classification and Information Control reviewed the draft manuscript for security purposes and confirmed it to be unclassified. Too many of the office staff had a hand in the review to allow the authors to name them all. They also offered helpful suggestions for improving the manuscript. Barbara Killian and John Hopkins of the Los Alamos National Laboratory reviewed the manuscript for content and offered the authors many helpful corrections and suggestions. Others who assisted the authors in obtaining research materials and photographs include Heidi Palombo and Helen Criares at the Department s Energy Technology Visuals Collection; John Flower, Dan Comstock, and Alan Carr at the Los Alamos National Laboratory; Maxine Trost and Beret Ranelletti at the Lawrence Livermore National Laboratory; Sharon Theobald, Janet Ortiz, and Lois Cooper at the Defense Threat Reduction Information Analysis Center; Eric Green at the Civil Defense Museum; Amy Beth Bennett at the Las Vegas Sun; Mike Femyer at Broadcasting 101; Alan Barnett and Doug Misner at the Utah History Research Center; and Kathryn Totton at the Special Collections Department of the University of Nevada, Reno Libraries. The Department s graphics and printing offices provided advice and input throughout the process of turning the manuscript into a printed document. Jennifer Johnson of the Office of History and Heritage Resources edited the manuscript, produced the layout and graphics, and advised the authors on the many things big and little needed for seeing the manuscript through publication. Finally, the authors would like to thank Jim Solit, director of the Department s Executive Secretariat, for his steadfast support of the Office of History and Heritage Resources and its staff. iv

7 Table of Contents Maps of the Nevada Test Site... Introduction: Operation Big Shot, April 22, Part I: Origins of the Nevada Test Site... Part II: Early Atmospheric Testing, Part III: The Trials and Tribulations of Atmospheric Testing, Part IV: Atmospheric Testing in the Balance, Part V: Atmospheric Testing Comes to a Close, Epilogue: From Moratorium to Atmospheric Test Ban Treaty, Appendix: United States Nuclear Tests, Acronyms and Abbreviations... Endnotes... vi v

8 Location of the Nevada Test Site and surrounding communities. Source: DOE, NNSA-Nevada Site Offi ce. vi

9 vii

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11 Introduction Operation Big Shot, April 22, 1952 Charlie promised to be a Big Shot, as the press dubbed the nation s twenty-fifth nuclear weapons test. With a projected explosive yield equivalent to thirty-three kilotons of TNT, Charlie would be the largest test conducted to date at the Nevada Proving Ground, formerly and again to be the Nevada Test Site. Charlie also was big in the sense that for the first time a nuclear weapons test would be held as an open shot that allowed a significant degree of public access. For the first time, as well, ground and airborne troops would conduct military maneuvers on a simulated nuclear battlefield following the shot. By 9:00 a.m. on April 22, 1952, at H-hour minus thirty minutes,* all was ready and in place for Charlie. Hundreds of observers, dignitaries, and reporters, previously banned from the site, had gathered on a small hill newly christened News Nob, about nine miles south of ground zero, to await the blast. Some were given high-density * In the military, the term H-hour is used for the hour on which a combat attack or operation is to be initiated. Minus thirty minutes indicates the time preceding the event. Source: U.S. Army Center of Military History, at Introduction: Operation Big Shot, April 22, 1952 goggles to view the burst, while others were told to turn away and shield their eyes. At the top of the Nob stood one of four television cameras prepared to broadcast the test to an anticipated audience of millions of viewers nationwide. Special arrangements made by Klaus Landsberg of KTLA, a Los Angeles television station (relatively close-by Las Vegas as yet having none), to provide pictures direct from the site using still primitive technology were, one reporter noted, almost heroic. To the north of News Nob, some 1,700 soldiers were positioned in five-foot-deep trenches 7,000 yards from ground zero, the closest by nearly half that any observer had ever been to a nuclear test. A thousand yards out, rockets, whose smoke trails would measure blast pressures, stood ready to be launched remotely only seconds before the blast. The B-50 bomber that would deliver the nuclear device, meanwhile, circled in a clockwise orbit at an altitude 30,000 feet above the Yucca Flat target area. 1 Surrounding ground zero stood an array of experiments for measuring Charlie s blast, thermal, and radiation effects on a variety of inanimate and animate objects. Trucks and tanks, some 35 parked aircraft, and numerous other pieces of military equipment and ordnance were placed at varying distances out from the detonation point to ascertain how well they would survive a nuclear attack. Effects on a minefield, 15 meters wide and extending out from ground zero to 1,830 meters, would determine the practicality of using nuclear weapons to clear mines. Measurements of motion and strain would be taken on four 50-foot tall coniferous trees anchored in concrete. Pigs, sheep, and mice served as surrogates for humans in various experiments. Anesthetized pigs would be used to measure thermal effects and skin burns. Mice would assist in determining radiation effects. Sheared sheep manned foxholes and trenches, with additional sheep tethered in the open. In one experiment, wood models of dogs were set up to measure blast effects on animals. Real humans, nine miles from ground zero, participated in a flash 1

12 KTLA Broadcasting - Charlie Shot A military helicopter, top, delivers an eight-foot microwave dish strapped to its side to a mountain top in the Nevada desert so that the signal can be relayed from the test site to the KTLA television studio in Los Angeles. Long-lens camera, middle, focuses on ground zero. Charlie shot, bottom, as seen on television. Source: KTLA 40th Anniversary Special, KTLA, through Broadcasting Battlefield of the Cold War: The Nevada Test Site, Volume I

13 Two soldiers crouch in their foxhole awaiting the blast. Source: DOE, NNSA-Nevada Site Offi ce. blindness experiment. Volunteers would look briefly directly at the flash, while others in a control group looked away, and then both groups would be required to read lighted instruments. 2 At H-hour minus ten minutes, troops moved into their trenches and, at minus two minutes, knelt, covering their faces with their hands and leaning against the forward trench wall. At minus one minute on News Nob, a voice over a loudspeaker instructed observers to put on goggles or face away from the target area. Minus thirty seconds... continued the announcer, Bombs away! As the device fell, one newsman reported how the observers breathed quickly in charged air as they stared transfixed toward ground zero and braced themselves for violence, anticipating the unexpected. The countdown continued as the voice of doom in charge of the loudspeaker droned on, five, four, three, two, one..., and Introduction: Operation Big Shot, April 22, 1952 then as the device detonated 3,447 feet above the target area a blinding flash of light that turned the desert a chalky white, as a Newsweek reporter described it, and, when the observers yanked their goggles off three seconds later, feeling the heat in their faces, the flash became a whirling ball of fire, kaleidoscoping into purples, yellows, and reds. At the same time, the observers witnessed the shock wave striking at ground zero destroying, you know, the planes and trucks parked there, if they haven t already been vaporized in the heat. From News Nob, they see a wall of dust, rising slowly into the air and streaking sideways along the desert ground as the shock wave travels, eventually rolling over the trenches and obscuring the troops from view. The voice in the loud speaker, meanwhile, warns, The shock wave will arrive in 30 seconds. When it hits News Nob, the shock is nothing but a sound... like a revolver fired at close range, then a lower and louder rumble lasting for seconds, and it s gone. The fireball, in the interim, has become a white cloud, edged yellow in the morning sun, trailed by a stalk which reached down toward the gray dust cloud blotting out ground zero. 3 An estimated 35 million television viewers were not as fortunate in what they saw. In Los Angeles, the blast pictures were more than satisfactory, but in other areas of the country many of those who watched never at any time had a plausible image of whatever it was that the camera was aimed at. Instead, they received an ever-changing series of geometrical designs, alternating with something that looked like showers of confetti. The first public detonation of an atomic weapon, the New York Herald Tribune noted, had produced an odd result: a revolutionary method of mass communication had blurred, rather than clarified, the impression of a revolutionary weapon of warfare. 4 In the trenches, the troops had yet another view. Crouched down, heads lowered and eyes covered, the soldiers experienced a very bright flash just like when you look straight into an arcwelding flare, one corporal noted, followed by a 3

14 Mushroom cloud rises over Yucca Flat as dust cloud begins to form below. Vapor trail of the U.S. Air Force B-50 drop plane is seen in the upper left. Above and behind the drop plane are vapor trails of four instrument-bearing aircraft that record scientifi c data on the atomic detonation. Source: DOE, NNSA-Nevada Site Offi ce. 4 Battlefield of the Cold War: The Nevada Test Site, Volume I

15 Soldiers and observers watch Charlie s mushroom cloud form. Source: DOE, NNSA-Nevada Site Offi ce. heat wave like you get when you open the door of a blast furnace. Ordered out of the trenches, the troops took in the strong odor of charred mesquite and awaited the shock wave. Twenty-one seconds after detonation, the shock wave, observed a lieutenant colonel, hit us... like a rolling surf r-r-r-r-rumpf. One veteran test observer described it as comparable to being hit in the face with a feather pillow. The accompanying sound, another noted, was loud enough to hurt my ears and the dust from the blast blotted out everything beyond a yard for a minute or so. The ordeal over, the young men were laughing and cracking jokes, according to one of three generals who witnessed the shot close in. The worst thing most of us got was a mouthful of dirt. Waiting for an hour while radiological monitors checked out the burst area, the troops then were transported by bus to a point about two miles southwest of the target area where they viewed the effects of the blast on a variety of military equipment and began a simulated assault, Introduction: Operation Big Shot, April 22, 1952 coming within 160 meters of ground zero, against enemy fortifications supposedly taken out by the detonation. They were met on the north side of the blast area by 120 paratroopers who had been air dropped by C-46 aircraft. Thirty paratroopers failed to show up when they jumped early, landing as far as 13 kilometers from the designated drop zone. 5 Effects from the blast varied, depending on the distance from ground zero. The flash blinded sheep tethered above ground at 900 and 2,000 yards away. Heat from the blast started vegetation fires out to 2,300 yards, leaving numerous yucca plants and Joshua trees smoldering, and gave lethal burns to sheared sheep tethered above ground at 900 yards. In foxholes, sheep at 900 yards received third degree burns and at 2,000 yards, in the open, first degree burns. Some trinitite, sand turned to green glass first encountered at the Trinity test, formed at ground zero. Radiation was lethal to sheep in the open at 900 yards. Military equipment 5

16 After the Charlie shot, members of the 82nd Airborne Division parachute into the area near ground zero. Source: DOE, NNSA- Nevada Site Offi ce. 6 Battlefield of the Cold War: The Nevada Test Site, Volume I

17 had wood, paint, and cloth burned at 900 yards. Trucks and jeeps at 2,000 yards suffered bent sheet metal and burned tires and cloth, with windshields broken out, but, one observer noted, might have been usable. At ground zero, a three-fourths ton truck was bent all out of shape and burnt. A light tank at ground zero had burns and bent and broken sheet metal but apparently had no crippling damage. Greater damage to the equipment might have been caused had not a fire truck, in the aftermath, put out many of the fires. 6 Operation Big Shot was a smashing success. As Atomic Energy Commission Chairman Gordon Dean observed as he watched Charlie s multicolored mushroom cloud rising overhead, it was a pretty sizeable bang for this country. More sobering was Federal Civil Defense Administrator Millard Caldwell s assessment of Charlie, a relatively small device compared to the megaton weapons that would follow. A bomb of this kiloton force, he noted, would have claimed onehalf million casualties in New York from blast, fire and radiation effects. Nonetheless, weapon scientists, military officials, and the media, even with some mixed feelings as to the uses that might be made of the spectacular display, all emerged well-satisfied with the results. Despite the faulty television reception, the American people also had gained a clearer notion of the significance of the events that were taking place at the test site. And significant they were. From 1951 through 1958, the United States conducted 120 tests at the Nevada Test Site. These tests directly contributed to the creation and manufacture of bigger, smaller, better, and safer nuclear weapons that greatly enhanced Truck between 400 and 500 yards from ground zero. Source: DOE, NNSA-Nevada Site Offi ce. Introduction: Operation Big Shot, April 22,

18 the capabilities of the nation s security forces and helped deter an all-out hot war. Warheads from a few kilotons to multi-megaton yields, warheads for bombs, guided missiles, ballistic missiles, depth charges, and hand-held bazookas were developed, refined, and stockpiled. On the downside, nuclear weapons testing also produced airborne radioactivity that fell outside the test site and, as the decade progressed, a worldwide uproar and clamoring for a ban on all tests. This combination of off-site radioactivity and an increasingly wary public ultimately would prove to be the undoing of atmospheric testing. 7 8 Battlefield of the Cold War: The Nevada Test Site, Volume I

19 Part I Origins of the Nevada Test Site The Nevada Test Site: What and Where The Nevada Test Site s primary mission has been the testing of nuclear weapons. From 1951 to 1992, when a worldwide moratorium on nuclear testing went into effect, the U.S. Department of Energy and its predecessor agencies conducted a total of 928 tests at the Nevada Test Site. The tests served a variety of national security purposes. These included design testing for the verification of new weapons concepts, proof-testing of existing weapons, effects testing to determine the impact of nuclear weapons on man-made objects and structures, plants and animals, and the physical environment, and experimental testing in the search for possible peaceful uses. The Nevada Test Site played a vital and central role in the development and maintenance of the Cold War nuclear arsenal. Although the site no longer plays host to nuclear weapons tests, the Department of Energy s National Nuclear Security Administration maintains the capability to resume testing should the necessity arise and continues to use the site for a variety of national security and other needs. 1 The Nevada Test Site consists of approximately 1,375 square miles of remote desert and mountain terrain owned and controlled by the Department of Energy and located in the southern part of the Great Basin northwest of Las Vegas. Elevations range from 3,280 feet at Frenchman Flat in the southeast corner of the site and at Jackass Flats in the southwest corner of the site to 7,675 feet on top of Rainier Mesa toward the northern border. The mountain ranges found on the site are generally lower in the south and higher in the north. Water or the lack thereof is the dominating climatic characteristic. The lower elevations have hot, dry summers and mild winters and average six inches or less of annual precipitation. Higher elevations receive somewhat increased precipitation and have lower temperatures. Temperature extremes on the site range from below zero to 110 degrees Fahrenheit. Despite the harsh climate, the Nevada Test Site is home to a surprising array of plants and animals. The site is in a transitional zone between the Great Basin and Mojave deserts. Species from both deserts, including those native to one but not the other, are found in the area. Kit fox and the sidewinder rattlesnake, common only in the Mojave Although not native, wild horses roam the higher elevations of the test site. Source: DOE, NNSA- Nevada Site Offi ce. Part I: Origins of the Nevada Test Site 9

20 Desert, live in the southern reaches of the site, and mule deer and the striped whipsnake, favoring a Great Basin desert environment, reside in the northern parts. Other animals found on site include coyotes, golden eagles, wild horses, mountain lions, and an occasional bighorn sheep and antelope. The range in elevation also helps provide for diversity in flora and fauna. Mojave Desert plants such as the creosote bush dominate the lower elevations. Plants of the Great Basin Desert prevail above 5,000 feet, with open piñon juniper and sagebrush woodland appearing at the 6,000 foot level. Between the two elevation extremes, sagebrush is the most common plant. Springs, the only perennial water sources on the site, sustain the wildlife population and are widely, if not abundantly, scattered across the area. The Nevada Test Site nonetheless is where it is for good reason. Few areas of the continental United States are more ruggedly severe and as inhospitable to humans. The site and the immediate surrounding area have always been sparsely populated. Only once prior to 1950, and then very briefly, did more than a few hundred people call the site home. In most periods of habitation, far fewer have lived there. Although no locale can be said to be ideal or optimal for nuclear weapons testing, the Nevada Test Site was perhaps the best continental site available for avoiding collateral damage and radiation exposure to plants, animals, and, most importantly, human beings off site. 2 Pre History and History to 1940 Even with a climate that has varied considerably over the last dozen millennia, the area that is now the Nevada Test Site has never been particularly conducive to human habitation and exploitation. The earliest cultural remains discovered on the site date back 10,000 to 12,000 years. More recently, the area was home to widely scattered groups of hunter gatherers currently known as Southern Paiute and Western Shoshone. They practiced a subsistence strategy designed to cope with a severe and unforgiving environment. Scarcity of game forced the population to subsist primarily on seeds and other vegetable foods. By the early twentieth century, most of the free roaming Native Americans had moved to surrounding towns or relocated to reservations. 3 Native American petroglyphs can be found on the test site. Source: DOE, NNSA-Nevada Site Offi ce. Explorers and pioneers first crossed the area in the mid-1800s but did not stay. The Old Spanish Trail, which was neither old nor Spanish, passed through the Las Vegas Valley south and east of the area that became the Nevada Test Site. First traversed in the winter of , the Old Spanish Trail served as a primary means of reaching the Pacific Coast until the termination of the war with Mexico in The earliest recorded entry onto the present test site was by an ill fated group of emigrants known as the Death Valley 49ers. Bound for the California gold fields in fall 1849, a party of Mormon families left the Salt Lake Valley too late in the season to cross the Sierra Nevadas on the more direct route across northern Nevada. They elected instead to head first toward southern California on the Old Spanish Trail. Persuaded by rumors of a shortcut, a splinter group left the trail near Enterprise, Utah, and headed west into unknown territory. Further splits 10 Battlefield of the Cold War: The Nevada Test Site, Volume I

21 Probable routes taken through the test site by the Death Valley 49ers. Note that on the map the entirety of what is now the Nellis Air Force Range is labeled as the A.E.C. Test Site. Source: Reprinted from George Koenig, Beyond This Place There Be Dragons: The Routes of the Tragic Trek of the Death Valley 1849ers through Nevada, Death Valley, and on to Southern California (Glendale, CA: The Arthur Clark Company, 1984). Part I: Origins of the Nevada Test Site 11

22 Remnants of Ranchers and Miners on the Test Site Tippipah Spring, top, with water storage tanks made from a boiler. Source: DOE, NNSA-Nevada Site Offi ce. Stone cabin at Whiterock Spring, top, with the remains of a corral and abandoned 1928 Buick. Source: DOE, NNSA- Nevada Site Offi ce. 12 Battlefield of the Cold War: The Nevada Test Site, Volume I

23 occurred in the wayward group as it became clear that there was no easy or readily distinguishable way. Although the exact routes taken remain debatable, all of the splinter parties clearly passed through the test site. One group entered the site via Nye Canyon on the eastern boundary, crossed over Frenchman Flat, and camped for nine days at Cane Spring, where from a nearby summit one member described the most wonderful picture of grand desolation one could ever see. Other groups crossed over Yucca Flat immediately to the north. All groups eventually left the site at Jackass Flats prior to their rendezvous at Death Valley where they remained stranded for several months. Fortunately, nearly all of the 49ers, after enduring extreme hardship, belatedly reached their destinations in California. 4 the test site west of Cane Spring and on the eastern edge of Jackass Flats. Mining operations in the area dated back at least to 1905, but the area remained Mining and ranching prompted the first meager settlement. During the last half of the nineteenth century, prospectors combed through virtually every valley, canyon, and outcropping in the American West. Although mining boom towns Tononpah, Goldfield, and Rhyolite sprang up to the west of the site in the first decade of the twentieth century, few discoveries of precious metals were made on the site itself. The earliest known claims were filed in March 1889 near Oak Spring, at the south end of the Belted Range in the far northern reaches of the site. Mining in this district continued off and on for the next fifty years, with turquoise and small amounts of gold and silver being the initial attraction. In 1917, copper ore containing some silver was shipped from the district as were minor amounts of tungsten. In the late 1930s, demand for tungsten, which was used in the production of armaments, increased with the approach of the Second World War, and several mining companies conducted sampling operations in deposits near Oak Spring. The site became known as the Climax Mine. 5 Nevada s last major mining rush occurred in the late 1920s at Wahmonie, located on what is now Mining activity at Oak Spring, 1920s. Source: Alvin McLane, from the Estate of B.M. Bower. Part I: Origins of the Nevada Test Site 13

24 Wahmonie Wahmonie, Nevada, 1928: top, in the early days of the strike; middle, fi rst women and fi rst gas station in Wahmonie; bottom, outdoor vendor supplying Wahmonie s miners. Source: top and bottom, Nevada Historical Society; middle, Atomic Testing Museum. 14 Battlefield of the Cold War: The Nevada Test Site, Volume I

25 quiet until the discovery of high grade silver gold ore in Established in February 1928, the Wahmonie mining camp grew to a population of some 500 within a month. Some miners arrived hauling small houses on trucks. Others came in cars loaded with provisions or even on foot pushing wheelbarrows tied down with goods. Many miners lived in small tents, but Wahmonie soon had boarding houses, tent stores, and cafés. Thirsty miners could avail themselves at the Silver Dollar Saloon or the Northern Club. Wahmonie s population peaked, however, in early summer at some 1,000 to 1,500, and by the end of the year it was clear that the strike was not as rich as had first been thought. Optimism faded, people began leaving, and the town went bust. Deterioration of Wahmonie began soon after the mines were abandoned when mining equipment was moved to other locations. The townsite nonetheless still retains some of its original features, including mine shafts, roads, tent pads, discarded lumber, and scattered mining debris. 6 The only other viable economic activity on what became the test site was open range grazing. Ranching on the site began in the late 1800s. Suitable forage grounds existed for both cattle and sheep, but access to water was a problem. Flow from the widely scattered springs was often minimal, and ranchers, to augment the supply of water, modified some springs and constructed water storage tanks. The remains of one such tank, made from a boiler, are found at Tippipah Spring, located near the center of the site. While ranchers and their families tended to live in nearby communities outside the present site boundaries, they built and maintained some structures on the site. At Whiterock Spring, in the north central portion of the site, an abandoned 1928 Buick still rests near stone cabins. Remnants of corrals can be found at a number of the springs on site. 7 The Las Vegas Bombing and Gunnery Range In the nearly hundred years since the 49ers first rumbled through on their way to Death Valley, not much interest had been shown, aside from the occasional prospector and intermittent grazing, in the area that would become the Nevada Test Site. In 1940, however, the precise characteristics that had made the region generally so unattractive the desolation, lack of water, and general uninhabitableness brought it to the attention of the federal government. With war looming, the United States had begun a major rearmament program. Part of this program involved locating bombing and gunnery training ranges for the Army Air Corps. On October 29, 1940, President Franklin D. Roosevelt established the Las Vegas Bombing and Gunnery Range. Encompassing more than three and a half million acres north and west of Las Vegas, the range stretched almost to Tonopah and included all of what is now the test site. More than ninety percent of the range was in the public domain, but a number of grazing, homestead, and mining claims made it difficult to take possession. In August 1941, the government began condemnation proceedings against the outstanding parcels of land. B-24 following an emergency landing. Source: Nellis Air Force Base, History Offi ce. Part I: Origins of the Nevada Test Site 15

26 World War II Military photograph of Las Vegas, Nevada, Airfi eld can be seen in background. Source: University of Nevada, Las Vegas, Special Collections. Document declassifi ed per E.O , Sec Las Vegas Army Air Field fl ightline, Source: Nellis Air Force Base, History Offi ce. 16 Battlefield of the Cold War: The Nevada Test Site, Volume I

27 The Army Air Corps decided to use most of the newly acquired range for an aerial gunnery school. Appropriate conditions for such a school existed, as one general put it, to a superlative degree. The range offered excellent year round flying weather, a strategic inland location, nearby mountains that could provide natural backdrops for cannon and machine gun practice, dry lake beds for emergency landings, and an existing airfield conveniently located on the outskirts of Las Vegas. Although the possible morale and morals hazard associated with the legal gambling and prostitution of Las Vegas gave the military pause, the advantages of the location far outweighed the disadvantages. Operations began in October 1941 as the courts finalized the land condemnations and federal marshals cleared the remaining stragglers off the range. The test site area s role was to serve as a setting for air to air gunnery practice. Gunners on airplanes used frangible bullets that broke upon impact, spattering paint so that gunners could see where their bullets had hit, as well as live fire against targets towed by other airplanes. This at times proved hazardous, and the site s backup role was to provide emergency landing services. The Army set up four emergency landing strips on the range. One was on Groom Lake east of the site. Another was on Pahute Mesa toward the north and west part of the site. The remaining two landing strips were further to the north and west on the range. The dry lake beds at Frenchman and Yucca flats could also serve as emergency strips. In addition, the Army established a forward base with a landing strip and other facilities at Indian Springs, a small hamlet with a service station and general store on the highway some ten miles southeast of the site. The end of the Second World War closed out training activities on the bombing and gunnery range. The Las Vegas Army Airfield briefly deactivated before reemerging, in response to political pressure and the growing Cold War threat, Part I: Origins of the Nevada Test Site as the Las Vegas Air Force Base in 1948, with a mandate to train pilots of single engine airplanes. The following year, the Air Force expanded the base s functions by adding a gunnery school. In April 1950, the base was renamed Nellis Air Force Base. As for the bombing and gunnery range, it stood largely unused throughout much of the late 1940s. 8 Neutrons, Fission, and Chain Reactions The Nevada Test Site might have remained a bombing and gunnery range forever had it not been for the revolutionary discoveries and insights of modern physics. In the early twentieth century, physicists conceived of the atom as a miniature solar system, with extremely light negatively charged particles, called electrons, in orbit around the much heavier positively charged nucleus. In 1919, the New Zealander Ernest Rutherford, working in the Cavendish Laboratory at Cambridge University in England, detected a high energy particle with a positive charge being ejected from the nucleus of an atom. The proton, as this subatomic particle was named, joined the electron in the miniature solar system. The number of protons in the nucleus of the atom determined what element the atom was. Hydrogen, with one proton and an atomic number of one, came first on the periodic table and uranium, with ninety two protons, last. This simple scheme did not, however, explain everything. Many elements existed at different weights even while displaying identical chemical properties. In other words, atoms of the same element, identical in every other way, could vary slightly in mass. The existence of a third subatomic particle, the neutron, so named because it had no charge, explained the differences. First identified in 1932 by James Chadwick, Rutherford s colleague at Cambridge, neutrons within the nuclei of atoms 17

28 bombarded uranium with neutrons the uranium nuclei changed greatly and broke into two roughly equal pieces. The pieces were lighter elements, one of which was a radioactive isotope of barium. Even more significantly, the products of the experiment weighed less than that of the original uranium nucleus. From Albert Einstein s formula, E=mc 2, which states that mass and energy are equivalent, it followed that the mass lost during the splitting process must have been converted into energy in the form of kinetic energy that could in turn be converted into heat. Calculations made by Hahn s former colleague, Lise Meitner, a refugee from Nazism then staying in Sweden, and her nephew, Otto Frisch, led to the conclusion that so much energy had been released that a previously undiscovered kind of process was at work. Frisch, borrowing the term for cell division in biology binary fission- named the process fission. Ernest Rutherford. Source: Argonne National Laboratory. of a given element could vary in number. The different types of atoms of the same element but with varying numbers of neutrons were designated isotopes. The isotopes of uranium, for instance, all have ninety two protons in their nuclei and ninety two electrons in orbit. But uranium 238, which accounts for over ninety nine percent of natural uranium, has 146 neutrons in its nucleus, compared with 143 neutrons in the rare uranium 235, making up only seven tenths of one percent of natural uranium. These insights aided greatly in the understanding of the building blocks of the elemental world, but an unexpected discovery by researchers in Nazi Germany just before Christmas 1938 radically changed the direction of both theoretical and practical nuclear research. In their Berlin laboratory, the radiochemists Otto Hahn and Fritz Strassmann found that when they Lise Meitner and Otto Hahn in their laboratory at the Kaiser Wilhelm Institute in Berlin. Source: Argonne National Laboratory. 18 Battlefield of the Cold War: The Nevada Test Site, Volume I

29 Uranium-235 fi ssion chain reaction. Fission of the uranium atom, it soon became apparent, had another important characteristic besides the immediate release of enormous amounts of energy. This was the emission of neutrons. The energy released when fission occurred in uranium caused several neutrons to boil off the two main fragments as they flew apart. Given the right set of circumstances, physicists speculated, these secondary neutrons might collide with other atoms and release more neutrons, in turn smashing into other atoms and, at the same time, continuously emitting energy. Beginning with a single uranium nucleus, fission could not only produce substantial amounts of energy but also lead to a reaction creating ever increasing amounts of energy. The possibility of such a chain reaction completely altered the prospects for releasing the energy stored in the nucleus. A controlled self sustaining reaction could make it possible to generate a large amount Part I: Origins of the Nevada Test Site of energy for heat and power, while an unchecked reaction could create an explosion of huge force. 9 The Atomic Bomb and the Manhattan Project The possible military uses that might be derived from the fission of uranium atoms were not lost on the best and brightest of the world s physicists. In August 1939, Einstein, with the help of Hungarian émigré physicist Leo Szilard, wrote a letter to President Roosevelt, informing him that recent research showed that a chain reaction in a large mass of uranium could generate vast amounts of power. This could conceivably lead, Einstein wrote, to the construction of extremely powerful bombs. A single bomb, the physicist warned, potentially could destroy an entire seaport. 19

30 Albert Einstein and Leo Szilard. Source: Institute for Advanced Study. Einstein called for government support of uranium research, noting darkly that Germany had stopped the sale of uranium and German physicists were engaged in uranium research. 10 President Roosevelt and his advisors reacted cautiously to the Einstein letter, providing only limited initial federal funding for isotope separation and chain reaction research. No one as yet knew whether an atomic bomb was even possible and, if it was, whether a bomb could be produced in time to affect the outcome of the war. Researchers discovered early on that uranium 238 could not sustain a chain reaction required for a bomb. Uranium 235, they knew, still might be able to, but separating uranium 235 from uranium 238 would be extremely difficult and expensive. The two isotopes were chemically identical and therefore could not be separated by chemical means. And with their masses differing by less than one percent, other means of separation would be very difficult. No proven method existed for physically separating the two in any quantity. At the same time, a second possible path to a bomb gradually emerged. Researchers studying uranium fission products at the Radiation Laboratory at the University of California in In response to Einstein s letter, President Franklin D. Roosevelt initiated government-sponsored research on uranium and fi ssion. Source: Franklin D. Roosevelt Presidential Library. Berkeley discovered another product, a new transuranium, man made element, named neptunium, with an atomic number of 93, created when uranium 238 captured a neutron and decayed. Neptunium itself decayed to yet another transuranium element. In February 1941, the chemist Glenn T. Seaborg identified this as element 94, which he later named plutonium. By May he had proven that plutonium 239 was 1.7 times as likely as uranium 235 to fission. The finding suggested the possibility of producing large amounts of the fissionable plutonium in a uranium pile, or reactor, using plentiful uranium 238 and then separating it chemically. This might be less expensive and simpler than building isotope separation plants. 11 Not until 1942, after the Japanese attack on Pearl Harbor had thrust the United States into World War II, was the decision made to proceed with a full-scale program to build an atomic bomb. 20 Battlefield of the Cold War: The Nevada Test Site, Volume I

31 Discovery of plutonium by the University of California, Berkeley, chemist Glenn T. Seaborg suggested a second path toward building an atomic bomb. Source: Department of Energy. James Chadwick and General Leslie R. Groves. Source: Department of Energy. Security requirements suggested placing the atomic bomb project under the Army Corps of Engineers. The Corps set up the Manhattan Engineer District commanded by Brigadier General Leslie R. Groves. The Manhattan Engineer District operated like a large construction company, but on a massive scale and with an extreme sense of urgency. Unique as well was the investment of hundreds of millions of dollars in unproven processes. By the end of the war, Groves and his staff expended approximately $2.2 billion on production facilities, towns, and research laboratories scattered across the nation. Secrecy and fear of a major accident dictated that the production facilities be located at remote sites. Due to ongoing uncertainties as to which processes would work, two distinct paths were chosen to obtain a bomb. One involved isotope separation of uranium 235. Groves located the production facilities for isotope separation at the Clinton Engineer Works, a ninety square mile parcel carved out of the Tennessee hills just west of Knoxville. (The name Oak Ridge did not come into widespread usage for the Clinton reservation until after the war.) Groves placed two methods into production: 1) gaseous diffusion, based on the principle that Part I: Origins of the Nevada Test Site molecules of the lighter isotope, uranium 235, would pass more readily through a porous barrier; and 2) electromagnetic, based on the principle that charged particles of the lighter isotope would be deflected more when passing through a magnetic field. Later, in 1944, Groves approved a production plant using a third method, liquid thermal diffusion, in which the lighter isotope concentrated near a heat source passing through the center of a tall column. Convection, over time, carried the lighter isotope to the top of the column. The second path chosen to build the bomb focused on producing large amounts of fissionable plutonium in a uranium pile. On December 2, 1942, on a racket court under the west grandstand at Stagg Field of the University of Chicago, researchers headed by the Italian-émigré physicist Enrico Fermi achieved the first self sustaining chain reaction in a graphite and uranium pile. Groves built a pilot pile and plutonium separation facility at the X 10 area of Clinton. Space and power generating limitations, however, precluded building the full scale production facilities at the site. Groves chose an alternate site near Hanford, Washington, on the Columbia River, because of its isolation, long construction season, and access 21

32 Manhattan Project Facilities K-25 Gaseous Diffusion Plant under construction at Clinton (Oak Ridge). Source: Department of Energy. K-25 from opposite end. Source: Department of Energy. Y-12 Alpha Racetrack at Clinton used the electromagnetic method to separate uranium isotopes. Spare magnets in left foreground. Source: Department of Energy. 22 Battlefield of the Cold War: The Nevada Test Site, Volume I

33 Manhattan Project Facilities Section of S-50 Liquid Thermal Diffusion Plant at Clinton. Source: Department of Energy. Workers loading uranium slug into face of air-cooled pile at the X-10 area of Clinton. Source: Department of Energy. Pile D at Hanford. Pile in foreground, water treatment plant in rear. Source: Department of Energy. Los Alamos laboratory mid-1940s. Source: Los Alamos National Laboratory Part I: Origins of the Nevada Test Site 23

34 would release the greatest possible amount of energy before being blown apart and dispersed in the explosion. The simplest way to accomplish this, which became known as the gun method, brought two subcritical masses of fissionable material together at high speed to form a supercritical mass. This was done using conventional artillery technology to fire one subcritical mass into the other. The gun method was used for the uranium 235 bomb. West end of Stagg Field at the University of Chicago. Location of CP-1, the world s fi rst nuclear pile or reactor. Source: Argonne National Laboratory. to hydroelectric power. Three water cooled reactors, designated by the letters B, D, and F, and corresponding separation facilities were built at the Hanford Engineer Works. Los Alamos scientists discovered, however, that the gun method would not work for plutonium. Impurities in the plutonium would set off a predetonation after a critical mass had been reached but before the optimum configuration had been attained. The result would be an ineffective, wasteful fizzle. As an alternative, scientists turned to the relatively unknown implosion method. With implosion, symmetrical shockwaves directed inward Much of the research work on producing plutonium, including design of the piles, took place at the Metallurgical Laboratory (Met Lab) in Chicago. Design and fabrication of the first atomic bombs were the responsibility of the newly established Los Alamos Scientific Laboratory, located at a virtually inaccessible site high on a mesa in northern New Mexico. The laboratory, headed by J. Robert Oppenheimer, attracted a remarkable array of scientists from universities across the United States. 12 Bomb Design Designing the bomb, or gadget as it came to be known, was not an easy task. Precise calculations and months of experimentation were required to obtain the optimum specifications of size and shape. For the bomb to work, sufficient fissionable material needed to be brought together in a critical mass, which would ignite a chain reaction that J. Robert Oppenheimer. Source: Reprinted by permission of the J. Robert Oppenheimer Memorial Committee. 24 Battlefield of the Cold War: The Nevada Test Site, Volume I

35 would compress a subcritical mass of plutonium, releasing neutrons and causing a chain reaction. Los Alamos, working with the Army Air Force, developed two bomb models by spring 1944 and began testing them, without the fissionable materials, with drops from a B 29 bomber. The plutonium implosion prototype was named Fat Man. The uranium gun prototype became Little Boy. Field tests with the uranium prototype eased remaining doubts about the artillery method. Confidence in the weapon was high enough that a full test prior to combat use was seen as unnecessary. The plutonium device was more problematic. It would have to be tested before use. 13 The Trinity Test The test shot, dubbed Trinity by Oppenheimer, was the most violent man made explosion in history to that date. Detonated from a platform on top of a 100-foot high steel tower, the Trinity device used about 13½ pounds of plutonium. The Trinity test also posed the most significant hazard of the entire Manhattan Project. Test planners chose a flat, desert scrub region in the northwest corner of the isolated Alamogordo Bombing Range in southern New Mexico for the test. The site was several hundred miles from Los Alamos, and the nearest off-site habitation was twenty miles away. Scientists, workers, and other observers, during the test, would be withdrawn almost six miles and sheltered behind barricades. Some apprehension existed that there would be a large scale catastrophe. Los Alamos scientists discussed the possibility that the atmosphere might be ignited and the entire earth annihilated but dismissed this as extremely remote. Dangers from blast, fragments, heat, and light, once one was sufficiently removed from ground zero, evoked little concern. Part I: Origins of the Nevada Test Site Tower for Trinity test. Source: Department of Energy. Not so with radiation. Prior to Trinity, scientists were well aware that the blast would create potential radiation hazards. Plutonium in the device would fission into other radionuclides. Neutrons would strike various elements on the ground and turn some into active nuclides. This radioactive debris would be swept with fission products into a growing fireball and lifted high into the air. Once in the atmosphere, they would form a cloud of intense radioactivity. Immediate radiation from the explosion and residual radioactive debris initially caused faint worry because of dilution in the air and the isolation of the site, but as the test drew closer planners realized, with some sense of urgency, that radioactive fallout over local towns posed a real hazard. Groves, in particular, feared legal culpability if things got out of hand. As a result, Army intelligence agents located and mapped everyone within a forty mile radius. Test planners set up an elaborate off-site monitoring 25